Reducing the degree of branching in polyacrylates via midchain radical patching: A quantitative melt-state NMR study

Gaborieau, M., Koo, S. P. S., Castignolles, P., Junkers, T., & Barner-Kowollik, C. (2010) Reducing the degree of branching in polyacrylates via midchain radical patching: A quantitative melt-state NMR study. Macromolecules, 43(13).

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Abstract

Degrees of branching were measured with 13C melt-state NMR in poly(n-butyl acrylates) synthesized in both the presence and absence of 1-octanethiol at various temperatures, and their precision calculated based on the signal-to-noise ratio of the quaternary carbon at the branching point. Nitrogen gas was used for all pneumatics. Samples synthesized with thiol were measured in 7 mm rotors at MAS rotational frequencies of 1.8 to 4.5 kHz, while samples synthesized without thiol were measured in 4 mm rotors at 9 kHz MAS. The relative standard deviation SD of DB was calculated from the signal-to-noise ratio of the quaternary carbon SNR. The accuracy of measured degrees of branching was ensured by full relaxation of the relevant signals between pulses. A significant decrease of branching was observed in the presence of a thiol during the polymerization process, experimentally confirming the patching effect of midchain tertiary radicals by the thiol.

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ID Code: 99238
Item Type: Journal Article
Refereed: Yes
Additional Information: Cited By :22
Export Date: 5 September 2016
CODEN: MAMOB
Correspondence Address: Gaborieau, M.; Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; email: m.gaborieau@uws.edu.au
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Keywords: Branching points, Degree of branching, Mid-chain radicals, N-butyl acrylate, Nitrogen gas, NMR studies, Octanethiol, Polymerization process, Quaternary carbon, Relative standard deviations, Rotational frequency, Tertiary radicals, Nitrogen, Rotors, Signal to noise ratio
DOI: 10.1021/ma100991c
ISSN: 00249297
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Deposited On: 22 Sep 2016 04:50
Last Modified: 06 Oct 2016 04:13

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